Apparatus and method for producing nanofiber

ABSTRACT

An object of the present invention is to provide an apparatus and method for producing a nanofiber by using a melt blown method improving productivity. 
     A pellet-shaped raw material (resin) fed into a hopper  2  is supplied and melted in a heating cylinder  3  heated by a heater  4 , and sent to a front part of the heating cylinder  3  by a screw  5  rotated by a motor  6 . The heating cylinder  3  is provided with a head portion  7 , and a high-pressure gas is ejected from the gas ejection hole  71  provided at a center of the head portion  7 . The molten resin sent to an end of the heating cylinder  3  is discharged from a resin discharge hole  73  having six superfine tubes provided in a downstream side of the resin ejection hole  73  through inside of the head portion  7 . The molten resin discharged from the resin discharge hole  73  is elongated and a fiber having nanometer-order diameter can be formed.

TECHNICAL FIELD

The present invention relates to an apparatus and a method for producinga nanofiber, which is capable of providing a high-quality nanofiber in asimple structure.

BACKGROUND OF THE INVENTION

In recent years, demand of a nanofiber is rapidly increasing inaccordance with expansion of use of a fiber having a nanometer-orderdiameter, namely a nanofiber. In accordance with expansion of use of thenanofiber, a special nanofiber has been required which is high inquality and corresponds to purpose. Regarding a nanofiber producingmethod, there are conventional methods such as an electrospinningmethod, a melt blown method or the like, and there are advantages anddisadvantages with each method.

Patent Document 1 as the above-mentioned background of the inventiondiscloses a method for producing a nonwoven fabric consisting of aplurality of kinds of fiber which is made by mixing a solutiondischarging fiber to a melt blown fiber. Specifically, by using asolution spinning unit which ejects a spinning solution discharged froma liquid discharge portion with a gas ejected from a gas dischargeportion, the solution discharge fiber made by discharging and fiberizingthe spinning solution is mixed into a fiber flow of a melt blown fiberdelivered from a nozzle by the melt blown method.

Furthermore, Non-Patent Document 1 discloses a nanofiber producingmethod using an electrospinning method. A conventional electrospinningmethod for producing the nanofiber requires solvent for swelling resin,however, Non-Patent Document 1 discloses a configuration for preventingflashing and explosion caused by using a solvent by swelling by a heatwithout using the solvent. Additionally, disadvantages of the nanofiberproducing method using the meld blown method are described in detail.

DESCRIPTION OF PRIOR ART Patent Literature

-   Patent Literature 1: Japanese Unexamined Patent Application    Publication No. 2010-185153

Non-Patent Literature

-   Non-Patent Literature 1: WEB-Journal No. 151 Nonwoven Fabric Extra    Issue (http://www.webj.co.jp/index.html)

SUMMARY OF INVENTION Problems to be Solved by the Invention

As described in the above-mentioned Non-Patent Literature 1, when afiber diameter is reduced in the nanofiber producing method of theconventional melt blown method, it is considered to apply a method forejecting high-temperature air at high speed and a method for suppressingdischarge of polymer. When the high-temperature air is ejected at highspeed, the fiber diameter is reduced but length of the fiber isshortened and shredded. On the other hand, when discharge of polymer issuppressed, an amount of production per unit time is extremely reduced.Accordingly, it is difficult for either method to achieve massproduction of the nanofiber having a good quality. In an electrospinningmethod, productivity has been improved, however, an apparatus has becomecomplicated, countermeasures is required for preventing flashing andexplosion, and cost of manufacture has become expensive.

The present invention was made in consideration of the above problems,and an object of the present invention is to provide an apparatus and amethod for producing a nanofiber which is capable of supplying a largeamount of the nanofiber having good quality in nanofiber producingmethod of a melt blown method, and improving safety by eliminatingfactor of flashing and explosion.

Means for Solving the Problems

According to the present invention, there is provided an apparatus forproducing a nanofiber comprising a liquid raw material discharge unitfor discharging a liquid raw material to a high-pressure gas flowejected from a high-pressure gas ejection unit, wherein a plurality ofthe liquid raw material discharge units are provided around thehigh-pressure gas flow ejected from the high-pressure gas ejection unit.

According to the present invention, there is provided an apparatus forproducing the nanofiber wherein the liquid raw material discharge unitcomprises an extruding unit for melting and extruding a raw material.

According to the present invention, there is provided an apparatus forproducing the nanofiber wherein the liquid raw material discharge unitcomprises a unit for supplying a dissolved raw material.

According to the present invention, there is provided an apparatus forproducing the nanofiber wherein the high-pressure gas ejection unit isprovided with a gas supply unit for supplying a high-pressure andhigh-temperature gas, and the high-pressure gas ejection unit ejects thehigh-temperature gas at a high pressure.

According to the present invention, there is provided an apparatus forproducing the nanofiber comprising an angle adjustment unit capable ofadjusting an installation angle of the liquid raw material dischargeunit to the high-pressure gas flow ejected from the high-pressure gasejection unit.

According to the present invention, there is provided an apparatus forproducing the nanofiber wherein at least two or more liquid raw materialdischarge unit are symmetrically provided to the high-pressure gasejection unit.

According to the present invention, there is provided an apparatus forproducing the nanofiber wherein the liquid raw material discharge unitsare equally provided around the high-pressure gas flow ejected from thehigh-pressure gas ejection unit.

According to the present invention, there is provided an apparatus forproducing the nanofiber wherein the high-pressure gas flow ejected fromthe high-pressure gas ejection unit is provided in a vertical directionto an installation surface of the nanofiber producing apparatus.

According to the present invention, there is provided a method forproducing a nanofiber by discharging a liquid raw material from a liquidraw material discharge unit to a high-pressure gas flow ejected from ahigh-pressure gas ejection means, wherein a discharge angle of theliquid raw material discharged from the liquid raw material dischargeunit to the high-pressure gas flow is adjusted, when a plurality of theliquid raw material discharge units provided around the high-pressuregas flow ejected from the high-pressure gas ejection unit discharge theliquid raw material.

According to the present invention, there is provided a method forproducing a nanofiber using a nanofiber producing apparatus comprising aheating cylinder to which a raw material is fed, a heating unit forheating the heating cylinder, and an extruding unit for extruding theraw material in the heating cylinder, wherein, an end portion of theheating cylinder is provided with a gas ejection hole for ejecting ahigh-pressure gas, a plurality of raw material discharge units fordischarging the raw material in melting state in the heating cylinderare provided around the gas ejection holes, the raw material fed in theheating cylinder is melted or melting state of the same is maintained byheating the heating cylinder by the heating unit, the raw material isdischarged from the raw material discharge unit by using the extrudingunit, an air current is generated by the gas ejected from the gasejection hole, and a fiber having nanometer-order diameter is obtainedby elongating the discharged raw material along with the air current ofthe ejected gas from the periphery.

Effect of the Invention

According to the present invention, a nanofiber having a smallerdiameter and good quality can be safely produced. Furthermore, when thenanofiber is produced, it is not necessary to apply an apparatus usinghigh voltage, and a problem of an amount of production per unit timewhich is disadvantage for the meld blown method can be solved byproviding a plurality of resin discharge unit.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a partial sectional side view showing an entire structure ofan embodiment 1 of a nanofiber producing apparatus according to thepresent invention.

FIG. 2 is an external plan view showing a head portion and a heatingcylinder of the nanofiber producing apparatus according to theembodiment 1 of the present invention.

FIG. 3 is an external front view showing an end of the head portion ofthe nanofiber producing apparatus according to embodiments of thepresent invention.

FIG. 4 is a cross-sectional view of the nanofiber producing apparatus inFIG. 3 , taken along the line A-A.

FIG. 5 is cross-sectional views of the nanofiber producing apparatus inFIG. 4 , taken along the lines B-B, C-C and D-D, respectively.

FIG. 6 is an explanatory diagram showing resin flow and gas flow in thehead portion of the nanofiber producing apparatus according to theembodiment 1 of the present invention.

FIG. 7 are explanatory diagrams showing (a) an example of a supportingstructure of a resin discharge unit and (b) another example of asupporting structure of the resin discharge unit of the nanofiberproducing apparatus according to the embodiment 1 of the presentinvention.

FIG. 8 is a side view showing the entire structure of an embodiment 2 ofa nanofiber producing apparatus according to the present invention.

FIG. 9 is a plan view showing the entire structure of the embodiment 2of the nanofiber producing apparatus according to the present invention.

FIG. 10 is a front view showing a structure of the head portion of theembodiment 2 of the nanofiber producing apparatus according to thepresent invention.

FIG. 11 is an explanatory diagram illustrating a basic concept of theapparatus and a method for producing the nanofiber according to thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, the preferred embodiment of the present invention will bedescribed in detail. The present invention is, needless to say, easilyapplicable to a structure other than the description of embodiments ofthe present invention within a scope not inconsistent with an object ofthe invention.

According to the present invention, a nanofiber is formed by supplying aliquid raw material to fluid (preferably, gaseous fluid) ejected in highpressure. In the description, a term “GAS” without specifyingcomposition means gases consisting of any composition and molecularstructure. Additionally, in the description, a term “raw material” meansall of materials applicable for forming the nanofiber. In theembodiments hereinafter, an explanation will be made for an exampleusing synthetic resin as the “raw material”, but not limited thereto,various kinds of composition material will be usable. The term “liquidraw material” in the description does not limit property of the materialto liquid, and includes “molten raw material” applicable for theembodiment 1 forming the nanofiber by melting and extruding a solid rawmaterial from an extruding unit. Moreover, the term “liquid rawmaterial” in the description also includes “dissolved raw material”applicable for the embodiment 2 which forms the nanofiber by dissolvingin advance a solid or a liquid raw material in a predetermined solventso that a predetermined concentration can be obtained, and by feeding byusing an appropriate means and discharging or extruding from a dischargeholes. The “liquid raw material” of the present invention needs propertyhaving viscosity enough to supply (eject, discharge) “raw material” fromsupplying holes (ejection holes, discharge holes), and “raw material”having such liquid property is described as “liquid raw material” in thepresent invention.

While detail description will be made hereafter, basic concept of thepresent invention is common to an apparatus and method for producing thenanofiber explained as the embodiments 1 and 2 of the present invention,and, as shown in FIG. 11 , it is configured to provide a high-pressuregas ejection unit 71 at a center thereof, and to make an installationangle of a plurality of discharge unit 73 a variable, which are arrangedaround a high-pressure gas flow 90 ejected from a high-pressure gasejection unit 71. In other words, a supply angle θ of the liquid rawmaterial to the high-pressure gas flow 90 is variable. The basic conceptof the present invention is, as shown in FIG. 11 , that the dischargeunit 73 a for discharging the liquid raw material is provided at thesupply angle θ to a central line 91 of the high-pressure gas flow 90,and the liquid raw material is discharged/supplied from a plurality ofthe discharge units 73 a toward the central line 91 of the high-pressuregas flow 90. The liquid raw material discharged/supplied from theplurality of discharge units 73 a is preferably provided to beintersected on the central line 91.

In FIG. 11 , arrangement condition of each component is as mentionedabove, and positional relationship is as follows. On the basis of aposition of the gas ejection hole (an opening nozzle) of thehigh-pressure gas ejection unit 71, “distance a” represents a distancefrom the gas ejection hole to the discharge unit 73 a, “distance b”represents a distance from the gas ejection hole to a point that the rawmaterials discharged from the discharge unit 73 a are intersected,“distance c” represents an opening diameter of the gas ejection hole,and “distance d” represents a distance between the gas ejection holes.

Herein, the discharge unit 73 a for discharging the liquid raw materialis provided at the supply angle θ to the central line 91 of thehigh-pressure gas flow 90. The raw material supply tangent angle θ isobtained from the following Equation (1)

tan θ=d/(b−a)  (1).

The raw material supply tangent angle θ is adjustable within a scope of0°<θ<90°. As an example, when the “distance a” is equal to 30 mm, the“distance c” is equal to 2 mm, the “distance d” is equal to 7 mm, andpressure of the ejected high-pressure gas is equal to about 0.15 MPa, θis preferably equal to 200 plus/minus 100.

The raw material supply tangent angle θ should be determined by the“distance a”, the “distance b”, and the “distance d” between the gasejection holes, and moreover, should be determined by relationship amongthe opening diameter “distance c” of the high-pressure gas ejectionhole, pressure and temperature of the ejected high-pressure gas.

According to the apparatus and method for producing the nanofiber of theembodiment 1 of the present invention, a pellet-shaped raw material(resin) fed into a hopper is supplied and melted in a heating cylinderheated by a heater, and sent to a front part of the heating cylinder bya screw rotated by a motor. The heating cylinder is provided with a headportion, and the high-pressure gas is ejected from the gas ejection holeprovided at a center of the head portion. The liquid molten raw material(molten resin) sent to an end of the heating cylinder is supplied(discharged) from the supply unit (the discharge unit) of the liquidmolten raw material (molten resin) having a plurality of superfine tubesprovided in a downstream side of the gas ejection unit, through insideof the head portion. A plurality of superfine tubes of the dischargeunits of the liquid molten raw material are provided equally around thegas ejection hole provided at a center. Thereby, the molten resindischarged from the discharge units of the liquid molten raw material iselongated and the fiber having the nanometer-order fiber can beobtained.

According to the apparatus and method for producing the nanofiber of theembodiment 2 of the present invention, configuration is made to ejectthe high-pressure gas from the gas ejection hole provided at a centerthereof, and the liquid dissolved raw material is discharged from aplurality of superfine tubes of the discharge units of the liquiddissolved raw material provided in a downstream side of the dischargeunits of the liquid dissolved raw material.

Embodiment 1

Hereinafter, entire structure of a nanofiber producing apparatusaccording to the embodiment 1 of the present invention will be describedin detail referring to FIGS. 1 to 3 .

A nanofiber producing apparatus 1 as shown in FIG. 1 according to theembodiment 1 of the present invention comprises a hopper 2, a heatingcylinder 3, a heater 4 as a heating unit, a screw 5 as an extrudingunit, a motor 6 as a driving unit, and a cylindrical head portion 7. Thehopper 2 feeds a resin (a granular synthetic resin having a fineparticle) to be a material for the nanofiber into the nanofiberproducing apparatus 1. The heating cylinder 3 heats and melts the resinsupplied from the hopper 2. The heater heats the heating cylinder fromoutside. The screw 5 is rotatably stored in the heating cylinder 3 andfunctions to move the molten resin to the end of the heating cylinder 3by rotating. The motor 6 rotates the screw 5 through a connecting unit61 (not shown in detail), and the head portion 7 is provided at the endof the heating cylinder 3. A nanofiber producing apparatus 1 furthercomprises a gas ejection hole 71 (an opening nozzle) for ejecting agaseous hot air from the center area, and a resin discharge unit insidethereof for discharging the molten resin described below from theperiphery of the gas ejection hole 71 (an opening nozzle). Thehigh-pressure gas is supplied to the head portion 7 through a pipe 81connected to a gas piping unit 8 as a gas supplying pipe for ejectingthe gas from the center area. The gas piping unit 8 is provided with aheating unit such as a heater or the like (not shown), and configurationis made to eject a hot air from the gas ejection unit 71 (the openingnozzle). The head portion 7 and the heating cylinder 3 are connected viaa seal portion 9 of a sheet member having a shape of O-ring and adoughnut-shape, and the molten resin is not leaked to outside of theapparatus thereby.

A plurality of heaters 4 provided at an outer circumference of theheating cylinder 3 is capable of controlling temperature separately orcollectively by a control unit (not shown). According to the presentembodiment, four heaters 4 are provided as shown in FIG. 1 , but notlimited thereto, modification is applicable to the number ofinstallation, size of each heater, and condition of arrangement inconformity to material and property of the resin to be used, andconditions of a diameter and length of the heating cylinder 3.

FIG. 2 is a plan view and FIG. 3 is a front view of a nanofiberproducing apparatus 1 according to the present embodiment. FIGS. 4 to 6are explanatory diagrams showing structure of the head portion 7.

The head portion 7 of the present embodiment, as shown in FIG. 3 , isconnected to the pipe 81 into which the high-pressure gas is fed fromthe outer circumference of the heating cylinder 3 through the gas pipingunit 8. The high-pressure gas from the pipe 81 is introduced to insideof the head portion 7 and ejected from the gas ejection hole (theopening nozzle: FIG. 3 ) provided at the center area. A plurality ofresin discharge units 73 are provided equally around the gas ejectionholes 71. According to the present embodiment, the resin discharge unit73 comprises a resin discharge needle 73 a and a resin discharge needlefitting unit 73 b having a structure for fitting the resin dischargeneedle 73 a to the head portion 7.

The head portion 7 shown in FIG. 3 comprises a heating cylinder coverunit 77 for covering the end portion of the heating cylinder 3 and aresin discharge unit holding ring 78 as a means for holding the resindischarge unit 73. The resin discharge unit holding ring 78 is fixed tothe heating cylinder cover unit 77 without fixing means such as a bolt(without reference number).

According to this resin discharge unit holding ring 78, if a pluralityof the resin discharge units 73 are provided around the gas ejectionhole 71 (the opening nozzle), there is achieved greatly increasingproductivity of the nanofiber having a uniform diameter and fiber lengthby arranging a plurality of resin discharge unit 73 at an equalinterval, an equal distance (“distance a” from the gas ejection hole),or an equal angle (discharge angle θ).

Referring to FIG. 11 , description will be made of positionalrelationship of the gas ejection hole 71 (the opening nozzle) and theresin discharge unit 73 provided around thereof. The gas flow 90 isejected from the gas ejection hole 71 provided at a center area of thehead portion 7. There is provided a plurality of the resin dischargeunits 73 provided around the gas flow 90, and the resin is ejected fromresin discharge holes of the resin discharge needles 73 a with adischarge angle θ to the gas flow 90. The resin discharge holes of theresin discharge needles 73 a are provided forward (in downstream sidealong with the gas flow 90 from the ejection holes 71) with “distance a”from the ejection hole 71. Each resin discharge hole of a plurality ofresin discharge needles 73 a is provided for discharging the resinforward with “distance b” from the ejection holes 71 (in the downstreamside along with the gas flow 90 from the ejection holes 71) so as tointersect resins.

Regarding an arrangement condition of a plurality of resin dischargeunits 73, it is also capable of forming a nanofiber having anununiformed diameter or fiber length by changing the number of the resindischarge units 73, an arrangement interval, an arrangement distance(“distance a” from the gas ejection hole), and an arrangement angle θ.According to use of the produced nanofiber, the arrangement condition ofthe resin discharge unit 73 such as the arrangement interval or the likemay be appropriately selected and changed.

FIG. 4 is a cross-sectional view of the head portion 7 of FIG. 3 , takenalong the line A-A. FIGS. 5 (a), (b) and (c) are cross-sectional viewsof main part of the head portion 7 of FIG. 4 , taken along the linesB-B, C-C and D-D, respectively. FIG. 6 is an explanatory diagram showinga flow passage A of the high-pressure gas and a flow passage B of themolten resin. As shown in FIGS. 4 to 6 , six resin flow passages 75 (anarrow B in the drawings) are provided in at equal interval correspondingto the resin discharge unit 73 in the head portion 7. The resindischarge unit 73 is connected to the heating cylinder 3 through theresin flow passage 75. The molten resin pressed by rotation of the screw5 flows into the resin flow passage 75 shown in the cross-sectionalview, taken along the lines D-D of FIG. 5(c), and through the resin flowpassage 75 shown in the cross-sectional view taken along the lines C-C,the molten resin flows in the resin discharge needle fitting unit 73 bshown in the cross-sectional view, taken along the lines B-B and isdischarged from the resin discharge needle 73 a. In this case, as shownin FIG. 4 , the gas flow passage 72 (an arrow A in the drawings) isprovided at a center of the head portion 7 so as not to interfere theresin flow passage 75 (an arrow B in the drawings). Additionally, asshown in a cross-sectional view, taken along the lines C-C of FIG. 5(b),the gas flow passage 72 is provided by changing a direction from outsideto inside of the head portion 7 through the any adjacent resin flowpassage 75. The gas piping unit 8 is connected to the gas flow passage72 through the pipe 81. The high-pressure and high-temperature gas fedfrom the gas piping unit 8 through such provided gas flow passage 72 andejected from the gas ejection hole 71 (the opening nozzle). The resinflow passage 75 and the gas flow passage 72 are provided in the headportion 7 so as not to interfere each other. The numeral reference 79 inFIG. 5(b) represents a screw portion 79 for fitting the pipe (the gasflow passage) 81 on the heating cylinder cover unit 77.

In order to adjust the arrangement condition of the resin discharge unit73 to the gas flow passage 72, a holding adjusting unit 74 for the resindischarge unit 73 is provided. A diameter of the resin discharge hole ofthe resin discharge needle 73 a in the resin discharge unit 73 is verysmall and the resin discharge needle 73 a is susceptible to the effectsof stress such as vibrations of an apparatus and pressure of the resin,and therefore, the arrangement condition of the previously mentionedresin discharge unit 73 may be changed and detachment may be occurredfrom the head portion 7. It becomes necessary to avoid stress on theresin discharge needle 73 a if an angle of the resin discharge needle 73a is adjusted and changed, and to make a structure not to detach theresin discharge needle 73 a from the head portion 7.

FIG. 7(a) is an explanatory diagram showing a support structure of theholding adjusting unit 74 for fixing the resin discharge unit 73 to theresin discharge unit holding ring 78, and for making a fitting angleadjustable. The resin discharge unit 73 comprises the resin dischargeneedle 73 a and the resin discharge needle fitting unit 73 b, and theresin discharge needle fitting unit 73 b is fixed on the resin dischargeunit holding ring 78 of the head portion 7 by screwing (not shown),engaging and using a fixing means such as a pin or the like. The resindischarge needle 73 a is provided with the holding adjusting unit 74.This holding adjusting unit 74 comprises a resin discharge needlegripping unit 74 a for gripping the resin discharge needle 73 a from theperiphery and a adjusting unit 74 b having an adjusting pestle 74 cwhich is retractable and provided penetrating from outside to inside ofthe head portion 7. By operating the adjusting unit 74 b, the adjustingpestle 74 c is advanced and retracted, and the resin discharge needlegripping unit 74 a is moved in a diameter direction of the head portion7. Thereby, the resin discharge needle 73 a can be fixed at a desiredposition and angle. By using such resin discharge hole support unit 74,the resin discharge unit 73 is adjusted so that the discharging moltenresin is discharged at a desired discharge angle to the ejection gasflow from the gas ejection hole 71, and is surely fixable at the angle.

This structure is useful as the adjusting unit of the discharge angle ofthe molten resin against the ejection has flow, and the resin dischargeneedle 73 a has a shape of very thin pipe. When the nanofiber producingapparatus 1 is operated, big vibration of the pipe may be occurred onthe top thereof by driving the motor 6 and the screw 5, and the holdingadjusting unit 74 can suppress the vibration effectively. In FIG. 2 ofthe present embodiment, six resin discharge units 73 are provided, andthe six holding adjusting unit 74 are also provided, but not limitedthereto, the number of thereof may be appropriately selected inaccordance with condition of the resin for use, an amount of production,property of products.

FIG. 7(b) shows another example of an angle adjusting function of theresin discharge unit 73. In this embodiment, the holding adjusting unit74 comprises a resin discharge needle gripping unit 74 d for grippingthe resin discharge needle 73 a from the periphery, and an adjustingunit (not shown) having an adjusting pestle 74 e which is retractableand provided penetrating from outside to inside of the head portion 7.By operating the adjusting unit, the adjusting pestle 74 e is advancedand retracted, and the resin discharge needle gripping unit 74 d ismoved in a diameter direction of the head portion 7. Thereby, the resindischarge needle 73 a can be fixed at a desired position and angle. Theresin discharge needle fitting unit 73 c is made spherical andcylindrical, a sliding surface 76 on which the resin discharge needlefitting unit 73 c can rotate or be rotatable is provided on the resindischarge unit holding ring 78 of the head portion 7, and the resindischarge needle fitting unit 73 c is provided. Thereby, an angle of theresin discharge needle 73 a can be easily adjusted and it becomescapable of adjusting the angle of the resin discharge unit 73 withoutconcern for dropout of the resin discharge needle 73 a.

Regarding the gas ejection hole 71 and the resin discharge unit 73, asshown in the drawings, the gas ejection hole 71 is provided in adownstream side from the resin discharge unit 73. According to thisstructure, the molten resin is gradually elongated along with adistribution of ejected gas flow ejected from the gas ejection hole 71,and a fiber having nanometer-order is obtained. By using the heatingunit not shown in the drawings, gas is ejected from the gas piping unit8 as a hot air. Accordingly, the resin discharged from the resindischarge unit 73 has a nanofiber larger in length and smaller in fiberdiameter in comparison with the case the normal temperature gas isejected.

Description will be made of a series of operation of the nanofiberproducing apparatus 1 having the above structure. the raw material (theresin) fed into the hopper 2 is melted in the heating cylinder 3 byheating by the heater 4, and sent to a front part of the heatingcylinder 3 by a screw rotated by the motor 6. The molten resin arrivedat the end of the heating cylinder 3 is discharged from the raw materialdischarge holes of six resin discharge needles 73 through six resin flowpassages 75 provided in the inside of the head portion 7. The dischargedmolten resin is carried along with an air current generated by thehigh-pressure and high-temperature gas supplied from the gas piping unit8 and ejected from the gas ejection hole 71. The nanofiber is formed byelongating the molten resin by the difference in velocity between rapidair current of the high-temperature gas and slow air retainedtherearound.

Embodiment 2

According to the embodiment 1 of the present invention, detaileddescription of the nanofiber producing apparatus was made in which thegranular synthetic resin having a fine particle is melted and used as araw material. As mentioned before, the liquid raw material of thenanofiber is not limited thereto, and a dissolved raw material may beused, which is prepared by dissolving the solid or liquid raw materialin the predetermined solvent in advance so as to obtain thepredetermined concentration. This is also called as the liquid rawmaterial. FIGS. 8 to 10 show the nanofiber producing apparatus forforming the nanofiber from the dissolved raw material. Same referencenumerals are used to the structure same as that in the embodiment 1.

According to the embodiment 2 of the present invention, a solventstorage unit 5A is used having function for extruding the dissolved rawmaterial with the predetermined pressure instead of using the hopper 2,the screw 5 and the motor 6 of the embodiment 1. The gravity caused bydifference in height may be applied as the predetermined pressure. Thehead portion 7A is connected to a solvent supplying hose 3A and the gaspiping unit 8. The unit for ejecting gas (illustration omitted) may beprovided in the gas piping unit 8 or be introduced from thehigh-pressure gas supply unit (not shown) to the gas piping unit 8. Asshown in FIG. 9 , the head portion 7A is provided with a gas flowpassage 72A and a gas ejection hole 71A as a flow passage of the gassupplied from the gas piping unit 8. In a similar manner, the headportion 7A is provided with a resin flow passage 75A as the flow passageof the dissolved raw material, and the resin flow passage 75A isconnected to the resin discharge unit 73. In a similar manner in theembodiment 1, the resin discharge unit 73 comprises the resin dischargeneedles 73 a as a discharge hole of the dissolved raw material and theresin discharge needle fitting unit not shown in FIGS. 8 to 10 . Thehead portion 7A is provided with the resin discharge unit holding ring78A. By providing the holding adjusting unit 74 comprising he resindischarge needle gripping unit 74 a and the adjusting unit 74 b havingthe adjusting pestle 74 c which is retractable and provided penetratingfrom outside to inside of the head portion 7A, the discharge angle ofthe resin discharge needle 73 a can be adjustable at all by the holdingadjusting unit 74 as same in the embodiment 1.

The nanofiber producing apparatus according to the embodiment 2 is, asshown in FIG. 10 , provided with two resin discharge units 73. Thenumber of resin discharge unit 73 is not limited to two, and three ormore resin discharge units 73 can be equally provided around the gasejection holes 71A. In this case, the resin discharge unit 73 ispreferably equally provided. The embodiment in the drawings shows ahorizontal ejection type, however, those skilled in the art can easilyconsider variations for ejecting vertically (from upward to downward, orfrom downward to upward) in a vertical direction from the gas ejectionhole 71A to the gas flow passage 72A.

In comparison with the structure of the embodiment 1, according to thepresent embodiment, the dissolved raw material is used which the rawmaterial is dissolved in the solvent, and the nanofiber producingapparatus can be composed without using a complicated component, such asthe heating cylinder, the motor, the screw and so on. Thereby, theapparatus becomes small in size and space can be saved. Additionally,since the apparatus becomes small in size, a portable nanofiberproducing apparatus can be obtained. In such a portable apparatus, thenanofiber can be formed by spraying the nanofiber to an area where thenanofiber should be attached, and use of a fiber can be expanded.

Though description was made of the embodiments of the present inventionin detail, the present invention is not limited to the prescribedembodiments, and various modifications may be possible within a scope ofthe present invention. For example, in the above embodiment, thehorizontal nanofiber producing apparatus is described which the moltenresin and the gas ejection hole are provided in a horizontal direction,however it is not limited thereto, there is no problem to arrange thevertical apparatus and method for producing the nanofiber in thedownward. If we adopt the vertical apparatus and method, an effect ofgravity can be effectively prevented. The extruding unit is explained asthe screw 5, however as a die cast method, there is no problem if thesolvent is supplied in order and intermittent extrusion is made by usinga piston, although countermeasures should be taken against interruptionof produced nanofiber. Furthermore, the gas ejection hole 71 may benozzle shape by forming in a taper shape so as to increase the pressurethereof. Two examples are raised and described about the structure ofadjusting the angles of the resin discharge needle 73 a, however, therecan be applied the structure capable of adjusting the angles of thebellows-type resin discharge unit and so on.

1. An apparatus for producing a nanofiber comprising a liquid rawmaterial discharge unit for discharging a liquid raw material to ahigh-pressure gas flow ejected from a high-pressure gas ejection unit,wherein a plurality of said liquid raw material discharge units areprovided around a center of the high-pressure gas flow ejected from saidhigh-pressure gas ejection unit.
 2. An apparatus for producing thenanofiber according to claim 1, wherein said liquid raw materialdischarge unit comprises an extruding unit for melting and extruding araw material.
 3. An apparatus for producing the nanofiber according toclaim 1, wherein said liquid raw material discharge unit comprises aunit for supplying dissolved raw material.
 4. An apparatus for producingthe nanofiber according to claim 1, wherein said high-pressure gasejection unit is provided with a gas supply unit for supplying ahigh-pressure and a high-temperature gas, and said high-pressure gasejection unit ejects said high-temperature gas in a high pressure.
 5. Anapparatus for producing the nanofiber according to claim 1, comprisingan angle adjustment unit capable of adjusting an installation angle ofsaid liquid raw material discharge unit to the high-pressure gas flowejected from said high-pressure gas ejection unit.
 6. An apparatus forproducing the nanofiber according to claim 1, wherein at least two ormore said liquid raw material discharge unit are symmetrically providedto said high-pressure gas ejection unit.
 7. An apparatus for producingthe nanofiber according to claim 1, wherein said liquid raw materialdischarge units are is equally provided around the high-pressure gasflow ejected from said high-pressure gas ejection unit.
 8. An apparatusfor producing the nanofiber according to claim 1, wherein thehigh-pressure gas flow ejected from said high-pressure gas ejection unitis provided in a vertical direction to an installation surface of thenanofiber producing apparatus.
 9. A method for producing a nanofiber bydischarging a liquid raw material from a liquid raw material dischargeunit to a high-pressure gas flow ejected from a high-pressure gasejection means, wherein a discharge angle of the liquid raw materialdischarged from said liquid raw material discharge unit to saidhigh-pressure gas flow is adjusted, when a plurality of said liquid rawmaterial discharge units discharge the liquid raw material to thehigh-pressure gas flow as a center ejected from said high-pressure gasejection unit.
 10. A method for producing a nanofiber using a nanofiberproducing apparatus comprising a heating cylinder to which a rawmaterial is fed, a heating unit for heating the heating cylinder, and anextruding unit for extruding the raw material in said heating cylinder,wherein, an end portion of said heating cylinder is provided with a gasejection hole for ejecting a high-pressure gas, a plurality of rawmaterial discharge units for discharging the raw material in meltingstate in said heating cylinder are provided around said gas ejectionhole, and a fiber having nanometer-order diameter is obtained by heatingsaid heating cylinder by said heating unit, by melting the raw materialsupplied in said heating cylinder or being maintained in a meltingstate, by extruding the raw material from said extruding unit anddischarging from said raw material discharge unit, by generating an aircurrent by the gas ejected from said gas ejection hole, and by carryingand elongating said discharged raw material along with the air currentof the ejected gas from the periphery.